@ckeditor/ckeditor5-engine
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The editing engine of CKEditor 5 – the best browser-based rich text editor.
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TypeScript
/**
* @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
*/
import { ViewPosition } from './position.js';
import { type ViewItem } from './item.js';
import { type ViewRange } from './range.js';
/**
* Position iterator class. It allows to iterate forward and backward over the document.
*/
export declare class ViewTreeWalker implements IterableIterator<ViewTreeWalkerValue> {
/**
* Walking direction. Defaults `'forward'`.
*/
readonly direction: ViewTreeWalkerDirection;
/**
* Iterator boundaries.
*
* When the iterator is walking `'forward'` on the end of boundary or is walking `'backward'`
* on the start of boundary, then `{ done: true }` is returned.
*
* If boundaries are not defined they are set before first and after last child of the root node.
*/
readonly boundaries: ViewRange | null;
/**
* Flag indicating whether all characters from {@link module:engine/view/text~ViewText} should be returned as one
* {@link module:engine/view/text~ViewText} or one by one as {@link module:engine/view/textproxy~ViewTextProxy}.
*/
readonly singleCharacters: boolean;
/**
* Flag indicating whether iterator should enter elements or not. If the iterator is shallow child nodes of any
* iterated node will not be returned along with `elementEnd` tag.
*/
readonly shallow: boolean;
/**
* Flag indicating whether iterator should ignore `elementEnd` tags. If set to `true`, walker will not
* return a parent node of the start position. Each {@link module:engine/view/element~ViewElement} will be returned once.
* When set to `false` each element might be returned twice: for `'elementStart'` and `'elementEnd'`.
*/
readonly ignoreElementEnd: boolean;
/**
* Iterator position. If start position is not defined then position depends on {@link #direction}. If direction is
* `'forward'` position starts form the beginning, when direction is `'backward'` position starts from the end.
*/
private _position;
/**
* Start boundary parent.
*/
private readonly _boundaryStartParent;
/**
* End boundary parent.
*/
private readonly _boundaryEndParent;
/**
* Creates a range iterator. All parameters are optional, but you have to specify either `boundaries` or `startPosition`.
*
* @param options Object with configuration.
*/
constructor(options?: ViewTreeWalkerOptions);
/**
* Iterable interface.
*/
[Symbol.iterator](): IterableIterator<ViewTreeWalkerValue>;
/**
* Iterator position. If start position is not defined then position depends on {@link #direction}. If direction is
* `'forward'` position starts form the beginning, when direction is `'backward'` position starts from the end.
*/
get position(): ViewPosition;
/**
* Moves {@link #position} in the {@link #direction} skipping values as long as the callback function returns `true`.
*
* For example:
*
* ```ts
* walker.skip( value => value.type == 'text' ); // <p>{}foo</p> -> <p>foo[]</p>
* walker.skip( value => true ); // Move the position to the end: <p>{}foo</p> -> <p>foo</p>[]
* walker.skip( value => false ); // Do not move the position.
* ```
*
* @param skip Callback function. Gets {@link module:engine/view/treewalker~ViewTreeWalkerValue} and should
* return `true` if the value should be skipped or `false` if not.
*/
skip(skip: (value: ViewTreeWalkerValue) => boolean): void;
/**
* Moves tree walker {@link #position} to provided `position`. Tree walker will
* continue traversing from that position.
*
* Note: in contrary to {@link ~ViewTreeWalker#skip}, this method does not iterate over the nodes along the way.
* It simply sets the current tree walker position to a new one.
* From the performance standpoint, it is better to use {@link ~ViewTreeWalker#jumpTo} rather than {@link ~ViewTreeWalker#skip}.
*
* If the provided position is before the start boundary, the position will be
* set to the start boundary. If the provided position is after the end boundary,
* the position will be set to the end boundary.
* This is done to prevent the treewalker from traversing outside the boundaries.
*
* @param position Position to jump to.
*/
jumpTo(position: ViewPosition): void;
/**
* Gets the next tree walker's value.
*
* @returns Object implementing iterator interface, returning
* information about taken step.
*/
next(): IteratorResult<ViewTreeWalkerValue, undefined>;
/**
* Makes a step forward in view. Moves the {@link #position} to the next position and returns the encountered value.
*/
private _next;
/**
* Makes a step backward in view. Moves the {@link #position} to the previous position and returns the encountered value.
*/
private _previous;
/**
* Format returned data and adjust `previousPosition` and `nextPosition` if
* reach the bound of the {@link module:engine/view/text~ViewText}.
*
* @param type Type of step.
* @param item Item between old and new position.
* @param previousPosition Previous position of iterator.
* @param nextPosition Next position of iterator.
* @param length Length of the item.
*/
private _formatReturnValue;
}
/**
* Type of the step made by {@link module:engine/view/treewalker~ViewTreeWalker}.
* Possible values: `'elementStart'` if walker is at the beginning of a node, `'elementEnd'` if walker is at the end
* of node, or `'text'` if walker traversed over single and multiple characters.
* For {@link module:engine/view/text~ViewText} `elementStart` and `elementEnd` is not returned.
*/
export type ViewTreeWalkerValueType = 'elementStart' | 'elementEnd' | 'text';
/**
* Object returned by {@link module:engine/view/treewalker~ViewTreeWalker} when traversing tree view.
*/
export interface ViewTreeWalkerValue {
/**
* Type of the step made by {@link module:engine/view/treewalker~ViewTreeWalker}.
*/
type: ViewTreeWalkerValueType;
/**
* Item between the old and the new positions of the tree walker.
*/
item: ViewItem;
/**
* Previous position of the iterator.
* * Forward iteration: For `'elementEnd'` it is the last position inside the element. For all other types it is the
* position before the item.
* * Backward iteration: For `'elementStart'` it is the first position inside the element. For all other types it is
* the position after item.
* * If the position is at the beginning or at the end of the {@link module:engine/view/text~ViewText} it is always moved from the
* inside of the text to its parent just before or just after that text.
*/
previousPosition: ViewPosition;
/**
* Next position of the iterator.
* * Forward iteration: For `'elementStart'` it is the first position inside the element. For all other types it is
* the position after the item.
* * Backward iteration: For `'elementEnd'` it is last position inside element. For all other types it is the position
* before the item.
* * If the position is at the beginning or at the end of the {@link module:engine/view/text~ViewText} it is always moved from the
* inside of the text to its parent just before or just after that text.
*/
nextPosition: ViewPosition;
/**
* Length of the item. For `'elementStart'` it is `1`. For `'text'` it is
* the length of that text. For `'elementEnd'` it is `undefined`.
*/
length?: number;
}
/**
* Tree walking direction.
*/
export type ViewTreeWalkerDirection = 'forward' | 'backward';
/**
* The configuration of {@link ~ViewTreeWalker}.
*/
export interface ViewTreeWalkerOptions {
/**
* Walking direction.
*
* @default 'forward'
*/
direction?: ViewTreeWalkerDirection;
/**
* Range to define boundaries of the iterator.
*/
boundaries?: ViewRange | null;
/**
* Starting position.
*/
startPosition?: ViewPosition;
/**
* Flag indicating whether all characters from
* {@link module:engine/view/text~ViewText} should be returned as one
* {@link module:engine/view/text~ViewText} (`false`) or one by one as
* {@link module:engine/view/textproxy~ViewTextProxy} (`true`).
*/
singleCharacters?: boolean;
/**
* Flag indicating whether iterator should enter elements or not. If the
* iterator is shallow child nodes of any iterated node will not be returned along with `elementEnd` tag.
*/
shallow?: boolean;
/**
* Flag indicating whether iterator should ignore `elementEnd`
* tags. If the option is true walker will not return a parent node of start position. If this option is `true`
* each {@link module:engine/view/element~ViewElement} will be returned once, while if the option is `false` they might be returned
* twice: for `'elementStart'` and `'elementEnd'`.
*/
ignoreElementEnd?: boolean;
}